Dishwasher pump assembly with sound damped impeller



Filed NOV. l2, 1965V F. E. LA FLAME ET AL DISHWASHER PUMP ASSEMBLY WITH SOUND DAMPED IMPELLER 2 Sheets-Sheet l THEIR ATTORNY Aug. 27, 196s F LA FLAME ET AL 3,398,866

DISHWASHER PUMP ASSEMBLY WTH SOUND DAMPED IMPELLER 2 Sheets-Sheet 2 Filed NOV. l2, 1965 INVENTORS Han/f E afiama THE/ ATTORNEY United States Patent O 3,398,866 DISHWASHER PUMP ASSEMBLY WITH SOUND DAMPED IMPELLER Frank E. La Flame, Dayton, and Richard E. Forrest, Lima, Ohio, assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Nov. 12, 1965, Ser. No. 507,435 1 Claim. (Cl. 222-333) ABSTRACT OF THE DISCLOSURE A dishwaser pump having a volute-shaped housing and an impeller with an axial inlet and a radial outlet and wherein the housing includes a cutoff shoulder in close spaced relationship with radial vanes on the impeller, the impeller having nine radial vanes equally spaced with one another on a highly nonrepetitive pattern to suppress sound frequencies at an impeller drive speed of 3400 r.p.m.s per minute.

This invention is directed to automatic dishwashers and .more particularly to means for reducing noise emissions from the dishwasher assembly.

In the development of domestic dishwashers, one problem has been to arrange the operative parts of the dishwasher to function in a manner that reduces the level of noise adjacent the dishwasher. It has been discovered that one of the most undesirable noise emissions is attributable to high-frequency impeller operation. This is especially the case in radial pumps having a large number of vanes wherein the impeller is driven at high speeds. In such cases, the action of the radial impeller with respect to its casing is such that a high-frequency sound is produced that is readily passed from the pump exteriorly of the dishwasher. The noise is at such a frequency that it does not blend with background sounds normally found in the operative environment of the dishwasher or in the environment in which a dishwasher is normally used. As a result, the high-frequency impeller noise is unusually pronounced and stands out as an undesirable characteristic of the operation of the unit.

Accordingly, an object of the present invention is to irnprove dishwashers of the type having a sump mounted radial pump including a volute casing having an impeller therein with a plurality of angularly offset vanes operable with respect to a cutoff shoulder or tongue of the volute casing to produce a high-frequency sound emission of substantial noise level by the provision therein of means for modulating the sound frequencies of pump operation so as to reduce the operating noise level of the dishwasher.

A further object of the present invention is to improve dishwashers of the type set forth in the preceding object by the provision of an impeller construction with unequally spaced vanes thereon that reduce the resultant noise level of pump operation by producing a wide range of sound frequencies from the pump.

Fur-ther objects and advantages of the present invention wil be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

FIGURE 1 is a view in front elevation of a dishwasher, partially broken away, including the present invention;

FIGURE 2 is an enlarged bottom elevational view of an impeller in the dishwasher of the present invention;

FIGURE 3 is -a chart defining the angular relationship between vanes on the impeller of FIGURE 2;

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FIGURE 4 is a view in vertical section through the sump region of the improved dishwasher showing the improved radial pump construction thereof; and

FIGURE 5 is a view in horizontal section taken along the line 5--5 of FIGURE 4.

Referring now to the drawings, in FIGURE 1 a dishwasher 10 is illustrated including an outer casing 12 surrounding a water container 14 forming a washing compartment 16. The water container 14'includes a bottom bulkhead 18 having a portion thereof bent downwardly at 20 to define a sump region 22 in the washing compartment 16. Within the sump region 22 is located a motor driven, plural pump assembly 24 having 1a support plate 26 thereof supportingly received within an annular resilient seal ring 28 supportingly received on inwardly turned edges of the downwardly deformed portion 20 of the bulkhead 18.

The motor driven pump assembly 24, :more specifically, is set forth in FIGURE 4 and including a drain pump 30 and a primary washing tiuid circulation pump 32. The drain pump 30 has a pumping chamber 34 formed by a downwardly bulged portion 36 in the support plate .26 with the pumping chamber 34 being separated from the sump region 22 by a cover plate 38 seated in a recess 40 formed in the upper surface of the support plate 26. The cover plate, as best seen in FIGURE 5, has an opening 42 formed therein dening an inlet opening to an inlet passageway 44 that communicates with one side of the pumping chamber 34. The pumping chamber 34 also communicates with an outlet passageway 46 therefrom which is in uid communication with a depending outlet member 48 that is connected to a exible drain Conduit 50.

Within the pumping chamber 34 is located a rotary lluid displacement member 52 including a central hub portion 56 connected to a shaft 58 from a two-pole high speed reversible electric motor 60 operable to drive the impeller 56 in one working embodiment at vapproximately 3400 revolutions per minute. The member 52 further includes a -plurality of circumferentially located radially outwardly directed blades 62 thereon to displace fluid from the pumping chamber 34 so as to draw it from the sump region 22 through inlet opening 42, inlet passageway 44 and thence discharge it through outlet passageway 46, outlet member 48 and the drain conduit'50 during a drain cycle of dishwasher operation during which time motor 60 is conditioned for counterclockwise rotation of member 52.

The central hub portion 56 of the member 52 has an elongated upwardly directed extension 64 thereon that passes through an opening 66 in the cover plate 38 to a point raised above thefsupport member 26, as best seen in FIGURE 4.

The primary washing uid circulation pump 32 includes an outer casing 68 having a top portion 70 and a bottom portion 72 shaped to form -a convoluted pumping chamber 74 therebetween as best seen in FIGURE 5. The casing portions 70, 72 are joined together by suitable means such as screws 75. The bottom portion 72 of the casing has a plurality of depending posts 76 thereon which are connected to the support plate 26 by screws 78 to locate an inlet opening 80 in the bottom casing portion 72 concentrically with respect to the upwardly directed extension 64. Above the inlet opening 80 in the pumping chamber I4 is located a radial impeller 82 having Ia depending neck 84 thereon telescoped over the extension 64 and fastened thereto by an elongated fastening element 86 that is threadably received at one end thereof within the hub portion 56 of the impeller 52. The opposite end of the fastener 86 holds a key 88 in place within a groove 90 in a head cover 91 of the impeller 82, as best seen in FIGURE 5, to lock the impeller on the extension 64 of member 52. By virtue of thisconnection, the impeller 82 is drivingly connected to the drive shaft 58 of the highspeed motor 60 for rotation therewith.

When the dishwasher is in a washing cycle of operation, the impeller 82 is rotated clockwise by the reversible motor 60 and fluid is drawn from the sump region 22 through the inlet opening 80 and thence is discharged through an outlet opening 92 in the top casing portion 70 to be discharged through a vertical discharge post 94 located on the top portion 70, as best seen in FIGURE 1, for passage to a distributing system (not shown) for directing fluid against articles located in the washing compartment 16.

In accordance with certain principles of the present invention, the impeller 82 has a plurality of vanes depending from the top thereof, as more specifically seen in FIGURE 2. More particularly, as seen in FIGURE 2, the impeller 82 includes vanes 96 through 112, each being characterized as having a radially innermost portion 114 thereof located in close spaced overlying relationship with the edge of the inlet opening 80 and a radially outermost portion 116 thereof located to be in close spaced relationship with a cutoff shoulder 118 of the casing 68 which serves as a lead-in tongue portion forming the start of the volute of the casing 68. Each of the vanes has a predetermined curvature between the radially innermost and radially outermost ends thereof.

In the past, in dishwashers of the illustrated type, the vanes of the radial pump have been equally angularly spaced about the impeller. In such cases, it has been found that when the impeller is driven by high-speed motors of the type discussed above to produce a high volume flow of fluid from the radial pump, as the equally spaced vanes are passed with respect to the cutoff shoulder 118, they cause a shearing action of fluid in the pumping chamber 74 between the vanes and shoulder that produces noise emission that, especially in the case of impellers having a large number of vanes, for example vanes in excess of nine in number, is of a high frequency and substantial noise level that is transmitted through the iluid in the pumping chamber 74 thence through the washing cornpartment 16 to the water container 14. The water container 14 and outer cabinet l2 typically in dishwashers are fabricated from light sheet metal material through which the high-frequency, high noise level sound is readily transmitted. The high-frequency sound, in the case of a nine vane radial impeller, is in excess of 500 cycles per second and is characterized by a substantial noise level on the decibel scale which, from a subjective standpoint, is quite noticeable since it is located out of the normal noise level found both in the operation of other parts of the dishwasher and in the environment where a dishwasher is normally located.

Accordingly, in the present invention the vanes 96 through 112 are located at unequal angles with respect to each adjacent vane through a predetermined schedule as illustrated in FIGURE 3. The angular spacing is around the circumference of impeller 82. Between adjacent ones of the blades, the angle is measured between like points on the adjacent ones of the blades. Accordingly, as each of the adjacent vanes passes with respect to the shoulder 118, the noise produced by the shearing action of the blades and the tongue 118 on fluid in the pumping chamber 74 is modul-ated by the creation of a plurality of side frequencies above and below the basic frequency normally present when the vanes are equally spaced.

It is found that modifying the angular spacing of the vanes, as illustrated, will produce -a frequency pattern that Will reduce noticeably the resultant noise level on the decibel scale. The reduction of the noise level is such that the operation of the primary wash fluid circulating pump 68 is reduced to a point where it is substantially unnoticed from a point exteriorly of the cabinet 12.

While the embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. In a dishwasher, the combination of, a container forming a Washing compartment, means forming a sump in said container, a bottom surface member in said sump, a volute-shaped pump housing supported on said bottom surface member including an inlet opening therein located above said bottom surface and facing said bottom surface, an impeller located within said housing including a circular head, nine radially outwardly directed vanes depending from said head, said casing having a cutoff shoulder therein forming the beginning of the volute in said casing, means for supporting said impeller in said casing to locate said vanes in close spaced relationship with said shoulder and in axial alignment with said inlet opening, drive means including a two-pole electric motor for rotating said impeller with respect to said shoulder at 3400 r.p.m., each of said nine vanes having a leading edge located adjacent an axial inlet to said impeller and a trailing edge located adjacent the radial outer periphery of said impeller, said vanes each having the same curvature between its leading and trailing edge, each of said trailing edges and said cutolf shoulder coacting to produce a lluid impulse within said pump housing with a frequency near 500 cycles per second, and said vanes being angularly spaced at like points on one another circumferentially around said circular head approximately as follows to prevent said fluid impulses from reinforcing noise produced by operation of said electric motor, rst and second ones of said vanes'spaced 39, second and third ones of said vanes spaced 38.5, lthird and fourth ones of said vanes spaced 41.5, fourth and fifth ones of said vanes spaced 40.5, fifth and sixth ones of said vanes spaced 40, sixth and seventh ones of said vanes spaced 39.5, seventh and eighth ones of said vanes spaced 40, eighth and ninth ones of said vanes spaced 41 ninth and said first of said vanes spaced 40.

References Cited UNITED STATES PATENTS 3,006,603 10/ 1961 Caruso et al 253-39 3,058,528 10/ 1962 Hiersch 253-39 3,244,105 4/ 1966 La Flame 103-3 FOREIGN PATENTS 165,330 4/ 1904 Germany. 421,964 1/ 1935 Great Britain.

ROBERT L. BLEUTGE, Primary Examiner. 

